feat: add implicit RECORD declaration for FOR loop cursors

Implement Oracle-compatible implicit cursor variable declaration in
FOR loops. Loop variables are now automatically created as RECORD type
when undefined identifiers are encountered, matching Oracle PL/SQL behavior.

Example:
  FOR cr IN (SELECT id, name FROM table) LOOP
    -- cr is implicitly declared as RECORD
    RAISE INFO 'id=%, name=%', cr.id, cr.name;
  END LOOP;

Previously required explicit declaration:
  DECLARE
    cr RECORD;
  BEGIN
    FOR cr IN (...) LOOP ...

Changes:
- Modified for_variable rule in pl_gram.y to call plisql_build_record()
  when T_WORD encountered instead of erroring
- Added comprehensive test suite with 6 test cases covering simple loops,
  nested loops, package procedures, scope isolation
- All 18 plisql regression tests pass

Author: rophy

src/pl/plisql/src/Makefile

@@ -58,7 +58,7 @@ REGRESS = plisql_array plisql_call plisql_control plisql_copy plisql_domain \
 	plisql_record plisql_cache plisql_simple plisql_transaction \
 	plisql_trap plisql_trigger plisql_varprops plisql_nested_subproc \
 	plisql_nested_subproc2 plisql_out_parameter plisql_type_rowtype \
-	plisql_exception
+	plisql_exception plisql_for_loop_implicit
 
 # where to find ora_gen_keywordlist.pl and subsidiary files
 TOOLSDIR = $(top_srcdir)/src/tools

src/pl/plisql/src/expected/plisql_for_loop_implicit.out

@@ -0,0 +1,119 @@
+--
+-- Test implicit RECORD declaration in FOR loops (Oracle compatibility)
+--
+-- Setup test table
+CREATE TABLE test_loop_data (
+  id NUMBER,
+  name VARCHAR2(50),
+  amount NUMBER
+);
+INSERT INTO test_loop_data VALUES (1, 'Item A', 100);
+INSERT INTO test_loop_data VALUES (2, 'Item B', 200);
+INSERT INTO test_loop_data VALUES (3, 'Item C', 300);
+-- Test 1: Simple FOR loop with implicit cursor variable
+-- Oracle: cr is implicitly declared as RECORD
+-- Expected: Should work (currently fails)
+DECLARE
+  total NUMBER := 0;
+BEGIN
+  FOR cr IN (SELECT id, name, amount FROM test_loop_data ORDER BY id) LOOP
+    RAISE INFO 'Processing: id=%, name=%, amount=%', cr.id, cr.name, cr.amount;
+    total := total + cr.amount;
+  END LOOP;
+  RAISE INFO 'Total amount: %', total;
+END;
+/
+INFO:  Processing: id=1, name=Item A, amount=100
+INFO:  Processing: id=2, name=Item B, amount=200
+INFO:  Processing: id=3, name=Item C, amount=300
+INFO:  Total amount: 600
+-- Test 2: FOR loop with different cursor variable name
+DECLARE
+  count_val NUMBER := 0;
+BEGIN
+  FOR rec IN (SELECT name FROM test_loop_data ORDER BY id) LOOP
+    count_val := count_val + 1;
+    RAISE INFO 'Row %: %', count_val, rec.name;
+  END LOOP;
+END;
+/
+INFO:  Row 1: Item A
+INFO:  Row 2: Item B
+INFO:  Row 3: Item C
+-- Test 3: Nested FOR loops with implicit variables
+BEGIN
+  FOR outer_rec IN (SELECT id, name FROM test_loop_data WHERE id <= 2 ORDER BY id) LOOP
+    RAISE INFO 'Outer: id=%, name=%', outer_rec.id, outer_rec.name;
+    FOR inner_rec IN (SELECT amount FROM test_loop_data WHERE id = outer_rec.id) LOOP
+      RAISE INFO '  Inner: amount=%', inner_rec.amount;
+    END LOOP;
+  END LOOP;
+END;
+/
+INFO:  Outer: id=1, name=Item A
+INFO:    Inner: amount=100
+INFO:  Outer: id=2, name=Item B
+INFO:    Inner: amount=200
+-- Test 4: Implicit cursor in package procedure
+CREATE OR REPLACE PACKAGE test_implicit_pkg IS
+  PROCEDURE process_data;
+END test_implicit_pkg;
+/
+CREATE OR REPLACE PACKAGE BODY test_implicit_pkg IS
+  PROCEDURE process_data IS
+    counter NUMBER := 0;
+  BEGIN
+    FOR item IN (SELECT id, name, amount FROM test_loop_data ORDER BY id) LOOP
+      counter := counter + 1;
+      RAISE INFO 'Item %: id=%, name=%, amount=%', counter, item.id, item.name, item.amount;
+    END LOOP;
+    RAISE INFO 'Processed % items', counter;
+  END process_data;
+END test_implicit_pkg;
+/
+-- Execute the package procedure
+BEGIN
+  test_implicit_pkg.process_data();
+END;
+/
+INFO:  Item 1: id=1, name=Item A, amount=100
+INFO:  Item 2: id=2, name=Item B, amount=200
+INFO:  Item 3: id=3, name=Item C, amount=300
+INFO:  Processed 3 items
+-- Test 5: Multiple FOR loops reusing same variable name (different scope)
+DECLARE
+  sum1 NUMBER := 0;
+  sum2 NUMBER := 0;
+BEGIN
+  FOR cr IN (SELECT amount FROM test_loop_data WHERE id <= 2) LOOP
+    sum1 := sum1 + cr.amount;
+  END LOOP;
+  RAISE INFO 'First loop sum: %', sum1;
+  -- cr should be implicitly declared again in this scope
+  FOR cr IN (SELECT amount FROM test_loop_data WHERE id > 2) LOOP
+    sum2 := sum2 + cr.amount;
+  END LOOP;
+  RAISE INFO 'Second loop sum: %', sum2;
+END;
+/
+INFO:  First loop sum: 300
+INFO:  Second loop sum: 300
+-- Test 6: Verify cursor variable doesn't leak outside loop
+DECLARE
+  x NUMBER;
+BEGIN
+  FOR loop_var IN (SELECT id FROM test_loop_data WHERE id = 1) LOOP
+    x := loop_var.id;
+  END LOOP;
+  -- This should fail: loop_var not visible here
+  RAISE INFO 'Value: %', loop_var.id;
+END;
+/
+ERROR:  "loop_var"."id": invalid identifier
+LINE 1: loop_var.id
+        ^
+QUERY:  loop_var.id
+CONTEXT:  PL/iSQL function inline_code_block line 8 at RAISE
+-- Cleanup
+DROP PACKAGE test_implicit_pkg;
+DROP TABLE test_loop_data;

src/pl/plisql/src/pl_gram.y

@@ -2329,12 +2329,24 @@ for_variable	: T_DATUM
 						$$.name = $1.ident;
 						$$.lineno = plisql_location_to_lineno(@1, yyscanner);
 						$$.scalar = NULL;
-						$$.row = NULL;
 						/* check for comma-separated list */
 						tok = yylex(&yylval, &yylloc, yyscanner);
 						plisql_push_back_token(tok, &yylval, &yylloc, yyscanner);
 						if (tok == ',')
+						{
 							word_is_not_variable(&($1), @1, yyscanner);
+							$$.row = NULL;
+						}
+						else
+						{
+							/* Oracle compatibility: implicitly create RECORD variable for FOR loop */
+							$$.row = (PLiSQL_datum *)
+								plisql_build_record($1.ident,
+													plisql_location_to_lineno(@1, yyscanner),
+													NULL,
+													RECORDOID,
+													true);
+						}
 					}
 				| T_CWORD
 					{

src/pl/plisql/src/sql/plisql_for_loop_implicit.sql

@@ -0,0 +1,109 @@
+--
+-- Test implicit RECORD declaration in FOR loops (Oracle compatibility)
+--
+
+-- Setup test table
+CREATE TABLE test_loop_data (
+  id NUMBER,
+  name VARCHAR2(50),
+  amount NUMBER
+);
+
+INSERT INTO test_loop_data VALUES (1, 'Item A', 100);
+INSERT INTO test_loop_data VALUES (2, 'Item B', 200);
+INSERT INTO test_loop_data VALUES (3, 'Item C', 300);
+
+-- Test 1: Simple FOR loop with implicit cursor variable
+-- Oracle: cr is implicitly declared as RECORD
+-- Expected: Should work (currently fails)
+DECLARE
+  total NUMBER := 0;
+BEGIN
+  FOR cr IN (SELECT id, name, amount FROM test_loop_data ORDER BY id) LOOP
+    RAISE INFO 'Processing: id=%, name=%, amount=%', cr.id, cr.name, cr.amount;
+    total := total + cr.amount;
+  END LOOP;
+  RAISE INFO 'Total amount: %', total;
+END;
+/
+
+-- Test 2: FOR loop with different cursor variable name
+DECLARE
+  count_val NUMBER := 0;
+BEGIN
+  FOR rec IN (SELECT name FROM test_loop_data ORDER BY id) LOOP
+    count_val := count_val + 1;
+    RAISE INFO 'Row %: %', count_val, rec.name;
+  END LOOP;
+END;
+/
+
+-- Test 3: Nested FOR loops with implicit variables
+BEGIN
+  FOR outer_rec IN (SELECT id, name FROM test_loop_data WHERE id <= 2 ORDER BY id) LOOP
+    RAISE INFO 'Outer: id=%, name=%', outer_rec.id, outer_rec.name;
+    FOR inner_rec IN (SELECT amount FROM test_loop_data WHERE id = outer_rec.id) LOOP
+      RAISE INFO '  Inner: amount=%', inner_rec.amount;
+    END LOOP;
+  END LOOP;
+END;
+/
+
+-- Test 4: Implicit cursor in package procedure
+CREATE OR REPLACE PACKAGE test_implicit_pkg IS
+  PROCEDURE process_data;
+END test_implicit_pkg;
+/
+
+CREATE OR REPLACE PACKAGE BODY test_implicit_pkg IS
+  PROCEDURE process_data IS
+    counter NUMBER := 0;
+  BEGIN
+    FOR item IN (SELECT id, name, amount FROM test_loop_data ORDER BY id) LOOP
+      counter := counter + 1;
+      RAISE INFO 'Item %: id=%, name=%, amount=%', counter, item.id, item.name, item.amount;
+    END LOOP;
+    RAISE INFO 'Processed % items', counter;
+  END process_data;
+END test_implicit_pkg;
+/
+
+-- Execute the package procedure
+BEGIN
+  test_implicit_pkg.process_data();
+END;
+/
+
+-- Test 5: Multiple FOR loops reusing same variable name (different scope)
+DECLARE
+  sum1 NUMBER := 0;
+  sum2 NUMBER := 0;
+BEGIN
+  FOR cr IN (SELECT amount FROM test_loop_data WHERE id <= 2) LOOP
+    sum1 := sum1 + cr.amount;
+  END LOOP;
+  RAISE INFO 'First loop sum: %', sum1;
+
+  -- cr should be implicitly declared again in this scope
+  FOR cr IN (SELECT amount FROM test_loop_data WHERE id > 2) LOOP
+    sum2 := sum2 + cr.amount;
+  END LOOP;
+  RAISE INFO 'Second loop sum: %', sum2;
+END;
+/
+
+-- Test 6: Verify cursor variable doesn't leak outside loop
+DECLARE
+  x NUMBER;
+BEGIN
+  FOR loop_var IN (SELECT id FROM test_loop_data WHERE id = 1) LOOP
+    x := loop_var.id;
+  END LOOP;
+  -- This should fail: loop_var not visible here
+  RAISE INFO 'Value: %', loop_var.id;
+END;
+/
+
+-- Cleanup
+DROP PACKAGE test_implicit_pkg;
+DROP TABLE test_loop_data;